1. Field of the Invention
This invention relates to a coaxial double piping structure for charging and discharging a heat source fluid in an air conditioning heat exchanger used as means for heat-exchanging air in a car. More particularly, the invention is effective when it is applied to an air conditioning heat exchanger of the type in which the air conditioning heat exchanger itself is so constituted as to be capable of rotating.
2. Description of the Related Art
An air-mix-type, that regulates the ratio of cold air and warm air by using an air-mix door and adjusts a temperature of air blowing to a passenger compartment, is a typical example of a temperature regulation system of an air conditioner for a car.
In this air-mix-type air condition for a car, Japanese Unexamined Patent Publications No. 2001-47845 and No. 2001-246921 disclose an air conditioner in which a hot-water-type heat exchanger for heating is so constituted as to be capable of rotating and is also allowed to play the role of the air-mix-door. Consequently, an air-mix-door can be eliminated and, at the time of maximum cooling, the hot-water-type heat exchanger for heating is operated and rotated to a position so that it does not operate as a resistance to a cold air flow and can increase the flow of cold air.
More concretely, according to the first reference No. 2001-47845, a hot water inlet pipe and a hot water outlet pipe on the fixed side are joined in a spaced-apart relation with a predetermined distance to one of the side surfaces of a disk-like member on the fixed side in a radial direction, and an inlet arc groove communicating with the hot water inlet pipe and an outlet arc groove communicating with the hot water outlet pipe are formed on the other side surface of the disc-like member on the fixed side.
On the other hand, two through-holes are formed in a spaced-apart relation in the rotation side disc-like member opposing the fixed side disc-like ember, and a hot water inlet pipe and a hot water outlet pipe on the rotation side that are integral with the hot-water-type heat exchanger for heating are connected to these through-holes in such a manner as to communicate the hot water inlet pipe on the rotation side with the inlet arc groove of the disc-like member on the fixed side and the hot water outlet pipe on the rotation side with the outlet arc groove of the disc-like member on the fixed side.
A seal material is arranged at each peripheral edge portion of the inlet and outlet arc grooves on the other surface of the disc-like member on the fixed side and is clamped between the fixed side disc-like member and the rotation side disc-like member to seal the hot water passage communication portion between the disc-like members.
According to the latter reference, i.e. Japanese Unexamined Patent Publication No. 2001-246921, the rotation side hot water inlet pipe integral with the hot water inlet tank of the heat exchanger for heating is sealed and connected to the fixed side hot water inlet pipe in such a manner as to be capable rotating, and the rotation side hot water outlet pipe integral with the hot water outlet tank of the heat exchanger for heating is sealed and connected to the fixed side hot water outlet pipe in such a manner as to be capable rotating.
In Japanese Unexamined Patent Publication No. 2001-47845, the hot water inlet pipe and the hot water outlet pipe are arranged in a spaced-apart relation in the radial direction of the fixed side disc-like member and the rotation side disc-like member. Therefore, the diameters of both disc-like members become unavoidably large.
Because the surface seal structure in which the seal member is clamped between disc-like members is employed, it is difficult to secure a uniform surface pressure throughout the entire length of the seal material and seal defect is likely to occur.
In Japanese Unexamined Patent Publication No. 2001-246921, the hot water inlet pipe and the host water outlet pipe protrude from the hot water inlet tank and the hot water outlet tank, respectively, in the mutually opposite directions. Therefore, a connection work of the fixed side pipe and the rotation side pipe must be carried out on both sides of the heat exchanger for heating and the assembly work factor is deteriorated. Because the hot water inlet pipe and the hot water outlet pipe protrude in mutually opposite directions, the arrangement performance of these hot water pipe is deteriorated, too.
The same problem occurs also when the cooling heat exchanger itself is allowed to rotate and to play the role of the air-mix door.